Would putting one of those thick framed canvases on the easel and taping paper to that instead of using a book work? Or maybe run a string through the books binding to hang it over the top? You can pick those up cheap at most op shops (either cheap generic prints or random people’s art attempts).

I never really liked working with charcoal, too messy and smudgy. But my artistic talents definitely do not lie in the realm of drawing.